In some examples, subsets of a NAND flash memory of a solid state device (SSD) exhibiting relatively high bit error rates may be retired, for example, as an error threshold is reached. While some NAND flash memories retire subsets of memory on a block-by-block basis, other NAND flash memories promote greater endurance by supporting retirement of individual physical memory pages of memory. However, employing sub-block granularity for retirement can lead to an undesirable increase in the amount of data that must be maintained, as well an increase in implementation complexity. Thus better memory management schemes are needed for memory products, such as SSD.